In general, tires are configured in such a manner as to include a plurality of tire rubber members and a plurality of reinforcement members which are mainly made up of cords. In a representative tire, as is shown in FIG. 5, respective portions such as an inner liner rubber portion 1, a tread rubber portion 2, side wall rubber portions 3, rim strip rubber portions 4 and the like are formed by rubber members which match properties required for the respective portions and these rubber members are combined with a carcass layer 5 which constitutes a cord-contained reinforcement member, a belt layer 6 and bead elements 7 to thereby make up a tire T1.
To mold rubber members which make up the respective portions, rubber materials were extruded continuously to be molded into rubber strips from an extruding machine via dies which match cross sectional shapes of the respective rubber members, and thereafter, the rubber strips so molded were cut to constant dimensions to thereby obtain target rubber members. In building a tire, the rubber members were sequentially affixed together on a rotational support element such as a building drum.
However, due to a problem that a rubber strip member distorts or contracts by the rubber strip member being extruded and molded by the extruding machine and cut to a fixed dimension, as is disclosed in Patent Document No. 1 and Patent Document No. 2 below, a non-vulcanized rubber strip material which has been extruded and molded into a ribbon shape is wound in an overlapping fashion in a tire circumferential direction on a rotational support element such as a building drum to thereby form a rubber member having a predetermined cross sectional shape.
Incidentally, in recent years, since tires have been exposed to stringent demands for increased tire performances such as low fuel consumption, increased wear resistance and kinetic performance, reduced noise level and the like, respective rubber members which make up a tire are each combined with a plurality of rubber materials which are suitable for increase in the various tire performances.
For example, since the inner liner rubber portion 1 is a member whose main object is to cut off the permeation of air, a rubber material having a small air permeability is used therefore. However, since the weight of the tire is increased in the event that the thickness of the rubber material is increased, a thin rubber material is preferably provided. However, in the event that a certain degree of thickness is not imparted to the inner liner rubber portion 1, the thickness thereof becomes uneven due to rubber getting out of position during a vulcanization process, leading to a fear that the function of an inner liner to cut of the permeation of air may not be fulfilled. Because of this, there occurs, for example, as is shown in FIG. 6, such a situation that a lower layer 1a of the inner liner rubber portion 1 which is provided on an internal side of a tire is made up of a rubber material having low air permeability, while an upper layer 1b thereof which is provided on an upper surface side of the lower layer 1a which confronts an external side of the tire is made up of a hard rubber member which prevents the movement of the lower layer 1a at the time of building under vulcanization.
The tread portion 2 is highly demanded to exhibit a low rolling resistance due to reduced fuel consumption, and an increase in the so-called wet performance is also demanded which includes braking performance and driving stability on a wet road surface from the viewpoint of safety. Furthermore, superior wear resistance is also demanded from the viewpoint of durability. These respective performances of low rolling resistance, wet performance and wear resistance tend to contradict to one another in view of rubber characteristics, and hence, it is difficult to make those performances compatible with one another. Then, in order to fulfill the various demands described above, for example, as is shown in FIG. 7, a lower layer 2a of the tread rubber portion 2 is made up of a rubber compound having a low rolling resistance, and an intermediate layer 2b which is made up of a rubber compound having an increased wet performance is formed on the lower layer 2a. Furthermore, a surface layer 2c made up of a rubber compound having an increased wear resistance is occasionally provided on the whole area or partially of an upper side thereof.
In addition, the side wall portion 3 needs to relax stress produced in the tread portion during the rotation of the tire, and hence, a high deflection resisting performance and kinetic performance are demanded, and the rubber material at the side wall portion 3 needs to be adaptable to the carcass layer 5 without moving out of position during building under vulcanization. To make this happen, at the side wall portion 3, for example, as is shown in FIG. 8, there may be a case in which a lower layer 3a which is made up of a rubber compound for preventing the movement of the rubber material during building under vulcanization is formed on an internal side of the side wall portion 3 which is brought into contact with the carcass layer 5, a surface layer 3c which is made up of a hard rubber compound is formed on a surface of the side wall portion of the tire T, and an intermediate layer 3b which is interposed between the lower layer 3a and the surface layer 3c is made up of a rubber compound having an increased kinetic performance.
When building the rubber members like the inner liner rubber portion 1, the tread rubber portion 2, and the side wall portion 3 which are each made up of a combination of a plurality of rubber compounds by winding spirally the aforesaid ribbon-shaped unvulcanized rubber strip material in an overlapping fashion, since the winding step needs to be implemented for each of the rubber compounds which make up the rubber member, there is caused a problem that the fabrication cycle time of each rubber member is lengthened to thereby reduce the productivity thereof.    Patent Document No. 1: JP-A-2000-202921    Patent Document No. 2: JP-A-9-29858